The first one listed is written by Hwang Kee and has detailed pictures with explanations of all of the 33 basic movements used. It also has the Kee Cho, Pyung Ahn, and Bassai forms. The beginning includes a history of Korean martial arts, a history of Tang Soo DO, the physics of Tang Soo Do, and a photocoppied version of the Moo Ye Dobo Ton GI.
The second book has pictures and descriptions of the basic movements but is mostly comprised of forms. It includes the Kee Cho, Pyung Ahn, Chil Sung IL to Sam, Bassai, Naihachi, and several more black belt level forms.